Cerebral palsy (CP) was commonly considered as a static encephalopathy with various clinical forms. Among them the dystonic form may occur alone (15%) or combined with other manifestations (e.g. spasticity). In a country-wide survey of dystonia in Israel, we discovered 7 cases in whom dystonia and/or spastic paraparesis appeared or worsened on the background of CP. The clinical deterioration occurred between 14 and 40 years of age and resulted in a bedridden state in 2 of the 7 patients. The occurrence of extrapyramidal features and/or progressive spastic paraparesis in patients with preexisting CP was not clearly recognized in the literature, although lately some reports suggested 'changing motor patterns' in patients with CP. It is hypothesized that in some cases the pathological substrate, occurring at the perinatal period, may slowly progress in adult life. The fact that the majority of the dystonic subjects were Ashkenazi Jews is reminiscent of the high gene frequency of idiopathic torsion dystonia in this group, and suggests that the genetic tendency may be triggered off by perinatal factors.